Question

我是iOS开发的新手，我正在尝试创建一个允许用户使用相机拍照的视图。

我想要发生的是当用户拍摄照片时，它会将其保存到相机胶卷中。我相信可以通过以下声明简单地完成：

//Let's say the image you want to save is in a UIImage called "imageToBeSaved"
UIImageWriteToSavedPhotosAlbum(imageToBeSaved, nil, nil, nil);

然而，我的问题是，如果用户离开视图然后返回到它，我仍然希望那张照片在那里。那么我如何取回之前拍摄/保存的相同图片，以便在重新打开视图时重新加载？

任何帮助都会很棒！谢谢。

Answer 1

此代码段将从相机胶卷中获取最新图像：reference link

ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];

// Enumerate just the photos and videos group by using ALAssetsGroupSavedPhotos.
[library enumerateGroupsWithTypes:ALAssetsGroupSavedPhotos usingBlock:^(ALAssetsGroup *group, BOOL *stop) {

    // Within the group enumeration block, filter to enumerate just photos.
    [group setAssetsFilter:[ALAssetsFilter allPhotos]];

    // Chooses the photo at the last index
    [group enumerateAssetsWithOptions:NSEnumerationReverse usingBlock:^(ALAsset *alAsset, NSUInteger index, BOOL *innerStop) {

        // The end of the enumeration is signaled by asset == nil.
        if (alAsset) {
            ALAssetRepresentation *representation = [alAsset defaultRepresentation];
            UIImage *latestPhoto = [UIImage imageWithCGImage:[representation fullScreenImage]];

            // Stop the enumerations
            *stop = YES; *innerStop = YES;

            // Do something interesting with the AV asset.
            [self sendTweet:latestPhoto];
        }
    }];
} failureBlock: ^(NSError *error) {
    // Typically you should handle an error more gracefully than this.
    NSLog(@"No groups");
}];

Answer 2

void UIImageWriteToFile(UIImage *image, NSString *fileName)
{
    NSArray *dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentDirectoryPath = dirPaths[0];
    NSString *filePath = [documentDirectoryPath stringByAppendingPathComponent:fileName];

    NSData *imageData = UIImagePNGRepresentation(image);
    [imageData writeToFile:filePath atomically:YES];
}

void UIImageReadFromFile(UIImage **image, NSString *fileName)
{
    NSArray *dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentDirectoryPath = dirPaths[0];
    NSString *filePath = [documentDirectoryPath stringByAppendingPathComponent:fileName];

    image = [UIImage imageWithContentsOfFile:filePath];
}

图像将以指定的名称保存到应用程序包的Documents目录中并从中读取。

用法示例：

UIImageWriteToFile(image, @"somephoto.png");

UIImage *fetchedImage;
UIImageReadFromFile(&fetchedImage, @"somephoto.png");

如何在iPhone相机胶卷上取回已保存的图片？

2 个答案: